function identify() {
    return this.name.toUpperCase();
}
function speak() {
    var greeting = 'hello,I am' + ' '+identify.call(this);
    console.log(greeting);
}
var me = {name:'cow'}
var you = {name :'big'}
let result1 = identify.call(me);
let result2 = identify.call(you)
console.log(result1,result2);
speak.call(me);
